Preventing corrosion damage from water ingress!


Our data loggers with PV covers are rated IP67, meaning they can be submerged under 1 meter of water for 30 minutes without water ingress. Editions with blind covers are rated IP68, allowing submersion under 2 meters of water for 2 hours without water ingress. In fact, our in-house testing shows that even the PV cover editions can withstand submersion under 2 meters of water for weeks. Despite this confidence in our waterproof enclosures, we occasionally receive units for repair due to water damage.

Here are some potential causes and solutions for water ingress:

Common causes of water ingress

  1. Mismatch between cable diameter and gland
    • Using cables that do not match the gland diameter can prevent the gland from sealing the cable entry.
  2. Incorrect placed gasket
    • The gasket must be placed correctly as the ML-x17 gasket is not symmetrical. Incorrect placement can lead to leaks. 
  3. Inaccurate cable entry cutouts
    • The above tests are conducted without cable entries as we provide our enclosure without them to allow clients the freedom to choose their own type of connectors. If cable entry holes are not drilled accurately, the gland or connector chassis might not seal properly. We offer laser cutting services to ensure precise cable entry cutouts. 
  4. Improperly tightened bolts
    • if bolts are not tightened enough, the gasket may not be sufficiently compressed to seal the enclosure

Environmental factors

The air trapped inside a sealed enclosure has at the time of closing a certain pressure, temperature and humidity. The trapped mass of air and the dissolved moisture it contains can’t go anywhere, so both air pressure and humidity will change when temperature changes.  A drop in temperature can cause dissolved moisture to form condensation, which can be mitigated by placing a silica gel bag inside.

Enclosures exposed to full sun can experience significant temperature swings, causing internal pressure variations up to several hundred hPa (even in the chilly Netherlands, see picture). This can create vacuums at night and overpressure during the day, stressing the gasket and enclosure. The vacuums can cause air containing dissolved moisture to be drawn in through tiny imperfections in cable seals, leading to condensation build-up. To avoid this, a venting plug is necessary to equalize internal with external pressures. However, keep in mind that the air breathed by a venting plug contains dissolved moisture as well. To avoid drawing in an unbalanced amount of humid air, ensure the venting plug is mounted in free air, sufficiently above any outdoor surface or vegetation, as stagnant air above surfaces or between vegetation can become very humid.

Recommendations

  1. Drill accurate cable entry/connector holes
    • Use precise methods, such as our laser cutting service, to ensure accurate cutouts.
  2. Use matching glands and cables
    • Ensure the gland matches the cable diameter to achieve a proper seal.
  3. Use venting plugs for enclosures exposed to full sun/extreme daily temperature swings.
    • A venting plug equalizes internal with external pressures. Ensure it is positioned sufficiently above any humid surface/vegetation. 
  4. Place the gasket correctly
    • Ensure the gasket is placed in the correct orientation to achieve a proper seal.
  5. Sufficiently tighten the bolts
    • Tighten bolts adequately to compress the gasket and seal the enclosure. 

By following these recommendations, the risk of water ingress can be significantly reduced, ensuring the longevity and reliability of our data loggers.

To monitor internal pressure, temperature and humidity, you could mount an ML-OI-AX-RH option board to be connected to a low-cost sensor based on the Bosch BME280 chip.